Medical respiratory apparatus typically includes a breathing circuit that is composed of a number of cooperating components, which connect together to form gas passageways that carry inhalation and/or exhalation gases. It is often desired to engage ancillary devices with the gas passageways of the breathing circuit, for example to monitor the temperature, flow rate and/or humidity of the gases in the breathing circuit. In particular, the ancillary devices are typically sensor probes, which are exposed to the flow of gas within the gas passageways of the breathing circuit.
In order to enable engagement of ancillary devices with the gas passageways of a breathing circuit, a suitable port is typically provided in one or more of the components that form the breathing circuit, the port being adapted to receive the ancillary device, such that the ancillary device is exposed to the gas within the breathing circuit. The port typically has the form of an opening in a wall of a flow passageway, with a cylindrical sleeve projecting outwardly therefrom. The cylindrical sleeve is typically adapted to receive the ancillary device with an interference fit, such that the ancillary device is exposed to the flow of gas within the breathing circuit. However, in view of the interference fit being the only means by which the ancillary device is retained, there may be a risk of dislodgement of the device from the port, and hence this conventional arrangement is not entirely satisfactory.
In an alternative arrangement, WO2004/108218 is arranged to secure the ancillary device in the opening by providing the opening with a resilient retaining arm that engages a corresponding ledge on the body of the ancillary device, with a snap-fit, to retain the ancillary device in the port. However, this arrangement requires the ancillary device to have a particular ledge formation for engagement with the retaining arm, and also makes insertion and removal of the ancillary device cumbersome for a user.
In addition, some types of ancillary devices must be disposed at a particular orientation, or within a particular range of orientations, relative to the direction of gas flow in order to function effectively. A particular example of this type of ancillary device is a flow sensor probe. Conventional arrangements for retaining and orientating a flow sensor probe comprise a cylindrical port for receiving the probe with an interference fit, and accompanying formations that engage with a portion of the probe during insertion, so as to require the probe to be in a particular orientation in order to be fully engaged with the port.
However, none of these types of arrangements have been found to be entirely satisfactory. In particular, the component disclosed in EP1374940 is arranged to orientate a flow sensor probe using a V-shaped locating projection on the probe, which is received within a corresponding V-shaped locating depression in the wall of the port with which the probe engages. The probe is particularly liable to be dislodged in this arrangement. In addition, the component disclosed in US2009/0282896 is arranged to orientate a flow sensor probe by providing a wall section adjacent to the port, which determines the orientation of the probe. In particular, the wall section is adapted to impinge on the housing of the probe, and hence prevent engagement of the probe with the port, unless the probe has a particular orientation relative to the port, and hence relative to the direction of gas flow.
There has now been devised an improved component of a respiratory apparatus which overcomes or substantially mitigates the above-mentioned and/or other disadvantages associated with the prior art.